Electric eels (they're actually knifefish, not eels) like many eel-like fish, look bigger than they are. Fish generally have all their organs situated between the mouth and the anus (duh...) and the rest of the fish behind that point is simply bone and muscle, i.e. tail. If you look at an EE, you see that the anus is very close to the front end of the fish; the more-than-80% of the fish behind that point is all bone, muscle and of course the specialized electricity-generating organ. But the heart, liver, stomach, intestines, etc....all the vital organs...are jammed into the very front end of the fish. Those organs are very small in comparison to the length of the fish overall.
Naturally, all the fish's tissues require oxygen and nourishment, but an EE doesn't require a huge amount of food. The EE I once owned was a bit over three feet in length when I decided that enough was enough and handed it on to a new owner. At that size, a few nightcrawlers or a couple of 3-inch feeder fish was a typical meal, which it would receive a couple times per week. The volume of food was not much more than that of a golfball; even that would result in a bulging belly that made the fish look ludicrously like a shillelagh, i.e. a long stick with a big knob on the end.
The fish had grown quite quickly, from about 12 inches to about 40, within just a couple years on a feeding schedule like this.
I often wonder what the correlation is between required food intake and frequency of major electrical discharges. I suppose if one looks upon the fish as a toy and is constantly provoking killing jolts out of it, maybe it would need more food? Don't know. The eel is constantly generating low-level navigational discharges that it uses to locate food, move around, etc.
As cool as these fish are...the ridiculous precautions required to make it safe to handle and maintain them just get old fast. Planted tanks require a lot more trimming and pruning and work than those without plants. Algae needs to be controlled yourself, rather than by means of algae-eating fish. The EE's don't like strong current, which prevents the use of circulating pumps and in turn results in a lot of debris on the bottom that requires vacuuming. All these things require reaching into the tank...and the fish actively investigates and is drawn to a hand or tool placed inside with it. I got several minor (but unpleasant) little inquisitive E-kisses...never a truly dangerous jolt...but the potential (pardon the pun) always exists.
